Disposable absorbent articles are used to absorb and retain body exudates, such as urine, fecal material, menses, and the like. A particular desired feature of disposable absorbent articles is the capability to acquire and hold body exudates to minimize leakage of body exudates from between the absorbent article and the wearer.
One particular problem associated absorbent articles (such as, e.g., diapers) is in the containment of low viscosity fecal matter in the rear waist region of the diaper. Leakage out the rear waist region occurs because many diapers are not able to form a seal in the small of the infant's back that is tight enough to contain, e.g., low viscosity fecal matter. This problem may be more significant for infants from zero to eight months old because infants in this age range normally have a high incidence of low viscosity fecal matter. This can also be a problem for older infants/children/adults when they are ill.
Although diapers with elastic waists have been used, that approach does not truly address the problem of sealing against the contours of the small of the back because elastic waists just bridge the generally concave contours of the small of the back. Other solutions have been proposed that involve creating an envelope along the rear waist, with an opening facing toward the crotch region of the diaper. Another approach to this problem involves adhesively sealing the diaper to the back waist region to prevent leakage. Other proposed solutions involve creating a fluid-filled pillow in the back waist region, some by elaborate mechanism to generate a gas to fill a chamber to serve as a conformable barrier in the back waist region. Examples of some of these approaches may be described in, e.g., U.S. Pat. No. 6,458,110 B1 (Lavon et al.) and International Publication No. WO 01/21120 (Reynolds et al.)
While another approach includes providing additional foam material along the back waist of the diaper in an attempt to resiliently conform to the contours of the small of the infant's back (see, e.g., U.S. Patent Application Publication No. US 2006/0058767 (Zhang et al.)), there are difficulties associated with this solution. The difficulties include the limited amount of lineal material of a thicker foam (e.g., material about 1 centimeter thick or greater) that can be delivered to the diaper manufacturing line in a conventional format, such as a roll of running length material. Providing thicker materials results in rolls having excessively large diameters or significantly shorter run times—to the point at which the use of roll-fed equipment is uneconomical.